With a good air cooler and a good enough case (Good airflow) you don't need to water cool. Water cooling has it's perks but it also has its downfalls. I just installed my first water cooler in a PC and I only did so because it's a mini ITX build (limited space) and I wanted to OC so the water cooler draws the heat away from my CPU and MOBO better (relocates it) and also allowed me to use non low profile ram....
long story short, I personally wouldn't water cool unless you have a specific situation that requires it. With a good quality air cooler you'll run almost the same temps